Intermittently operated valve tappet



Q 1950 F. M. KINCAID, JR 2,526,239

INTERMITTENTLY OPERATED VALVE TAPPET Filed April 25, 1946 2 Sheets-Sheetx INVENTOR. FRANK M. mama-m.

AT TDRNEY Oct. 17, 1950 F. M. KINCAID, JR

INTERMITTENTLY OPERATED VALVE TAPPET 2 Sheets-Sheet 2 Filed April 23,1946 INVENTOR. FRANK M. KINCAIQJR.

ATTEIRNEY Patented Oct. 17, 195

INTERMITTENTLY OPERATED VALVE TAPPET Frank M. Kincaid, Jr., MountainLakes, N. J assignor to Wright Aeronautical Corporation, a

corporation of New York Application April 23, 1946, Serial N0. 664,373

2 Claims.

valves are operated by mechanism including cam means or other rotatablemeans driven by the engine at half the crankshaft speed. That is, inthese prior art constructions, the valve operatin cams or otherrotatable means are driven at half engine speed in order to operatethevalves once every two revolutions of the engine. It is an object ofthis invention to provide a novel and simple valve operating mechanismin which the valve operating cam or cams or other rotatable means aredriven at engine speed and the valve operating mechanism is so arrangedthat the valves are only operated once every twocrankshaft revolutions.With this construction, the special cam shafts and cam drives of theprior art, made necessary because of the difference between the engineand cam speeds, are eliminated. This feature is particularly importantin aircraft engines because of the resulting saving in weight.

Other objects of this invention will become apparent upon reading theannexed detailed description in connection with the drawing in which:

Figure 1 is a sectional view through a portion of an internal combustionengine embodying the valve operating mechanism of the invention;

Figure 2 is a sectional view along line 2-2 of Figure 1;

Figure '3 is a sectional view along line 3-3 of Figure 1;

Figure 4 is an enlarged sectional view along line 44 of Figure 1; and

Figure 5 is an enlarged sectional view illustrating the valve tappetmembers with their splines in sliding engagement. 7

Referring to the drawing, an engine cylinder of a four-stroke cycleinternal combustion engine, illustrated in part at I0, is provided witha valve I2 to be operated once every two revolutionsof the enginecrankshaft. The'valve I2 is provided with a valve spring I4 for urgingthe valve in a closing direction. A rocker member I6, pivotally mountedin a cylinder head rocker box I8, has one arm engaging the stem of thevalve l2 and has its other arm operatively engaging a push rod' 20. Acylindrical housing 22 is disposed about the push rod between the rockerbox I8 and the engine crankcase 24. The engine crankcase is providedwith a hollow member 26 to which the housing 22 is secured in the usualmanner.

The lower end of the push rod 20 is received in a spherical seat 28 of avalve tappet comprising telescopic members 30 and 32. For convenience,the tappet members 30 and 32 are'referred to as the upper and lowertappet members respectively. The lower tappet member 32 is provided witha cam follower roller 34 disposed in engagement with a rotatable cammember 36 driven by the engine in the direction indicated in Figure 3.The cam member 36 is provided with a cam lobe for actuating the valvetappet once each crankshaft revolution. The valve tappet is slidablymounted in a guide 40 secured to the engine crankcase 24. The guide 40extends downwardly about the roller 34 and is provided with slots 42through which the roller projects thereby preventing rotation of thevalve tappet member 32 relative to the guide 40 and engine crankcase.The valve tappet members 30 and 32 are urged apart by a spring 44 totake up the clearance in the valve operating mechanism and to maintainthe cam follower roller 34 in contact with its cam.

The valve tappet member 32 is provided with internal axial splines 46adapted to slide between external axial splines 48 on the valve tappetmember 38 when the splines 46 are alined with the spaces between splines48 as illustrated in Figure 5. In addition, a member 50, rigidly carriedby the member 26 and engine crankcase'24, is provided with axial splines52 between which the axial splines 48 are arranged to slide as soon asthe upper tappet member 30 moves upwardly from its downward or valveclosed position illustrated in Figure 1. In this way, as soon as thetappet member 30 is raised from its retracted position, rotation of thetappet member 30 is prevented by meshing engagement of the axial splines48 and 52. Also provided is a member 53 to act as a guide or pilot forthe upper tappet member 30.

The lower tappet member 32 is provided with an annular member 54 securedthereto against axial movement by a snap ring 56. The member 54 is freeto rotate relative to the tappet member 32 and is provided with axialsplines 58 disposed in meshing engagement with the splines 48 of theupper tappet member 30 thereby preventing relative rotation between theannular member 54 and the tappet member 30. The annular member 54 isalso provided with external helical splines 60 engaged with internalhelical splines 62 on a ratchet wheel 64. The ratchet wheel 3 as isprovided with ratchet teeth 66, the number of the teeth 66 being equalto twice the number of the splines 48.

A pawl 68 is engageable with the ratchet teeth to inhibitcounterclockwise rotation of the ratchet wheel 64 as viewed in Figure 2.The pawl 68 is pivotally mounted on a member slidably carried within arecess in the member 26 and urged outwardly by a spring 12. In addition,a spring i4 acts on the pawl 68 for rotating the pawl 88 into engagementwith the ratchet wheel fi l. The orientation of the helical splines 62is such that axial upward motion of the annular member 54 efiectsclockwise rotation of the ratchet wheel 64 as viewed in Figure 2 anddownward axial movement of the member effects counterclockwise rotationof the ratchet wheel 64.

With the aforedescribed construction, and with the tappet members havingthe relative rotative positions illustrated in Figure 2, when the camlobe 38 actuates or raises the tappet member 32, the upper ends of thesplines 46 abut against the lower ends of the splines 48 whereby theupper tappet member 39 is raised and the valve 12 is opened. As soon asthe tappet member 30 is raised slightly, the splines 48 engage betweenthe splines 52 to prevent rotation of the tappet member 3i} and annularmember 54. The resulting upward axial motion of the annual member 54effects clockwise rotation of the ratchet wheel 64.

lead or" the helical splines 52 is so chosen that, when the tappet israised to its maximum by a cam lobe 38, the ratchet wheel 6t beenrotated one tooth whereby the pawl rides over and enga es the next tooth'58. Then, when the cam lobe 38 moves beyond the cam follower roller 3d,the tappet returns to its lowered or retracted position. During thisreturn movement, the downward axial movement of the annular member 54now forces the ratchet wheel 54 to rotate counterclockwise therebycompressing and storing energy in the spring 2 at the same time thespring 14 maintains the pawl 53 in engagement with the particular tootht6 engaged during this return movement of the tappet.

At the end of the return movement of the tappet, the splines 48 and 52disengage, thereby freeing the upper tappet member 39 for rotationwhereupon the spring ?2 through the pawl #53 rotates-the ratchet wheelM, annular member and upper tappet member 39 through an arccorresponding to one ratchet tooth-that is, through an angle equal to360 divided by the number of ratchet teeth 6%. A shoulder 16 iimits theextent to which the pawl 58 and spring i2 can rotate the ratchet wheel.Since the number of splines 48 is only equal to one-half the numberoi'ratchet teeth 66, this rotation of the tappet member 36 relative tothe lower tappet member 32 brings the splines 58 into alineinent withthe spaces between the splines Accordingly, the next time the cam lobe38 raises or actuates the cam follower roller 34', the tappe member 32is raised, but its splines d6 now siide between the splines 48 so thatthe upper tappet i ember 3 3 is not raised and the valve 52 remainsclosed.

During this second tappet actuation, the meshing engagement of thesplines 46 and 48 looks the tappet member 35 and annular member 54 tinstrotation. Also, the annular member 54 is forced axially upward by thenow'abutting engagement of the splines #16 and 58. Therefore, asbefora'the ratchet wheel 64 is forced to rotate clockwise through anangle corresponding to one ratchet tooth whereupon the pawl 63 ridesover and engages the next ratchet tooth 66. Then, upon the return ordownward stroke of the tappet member 32, the ratchet wheel 54 rotatescounterclockwise thereby compressing the spring 12. Upon completion ofthis return stroke, the splines 4'6 and 48 move out of meshingengagement whereupon the spring 12 again rotates the tappet member 38,annular member 54 and ratchet wheel 64 through an angle corresponding toone ratchet tooth whereby the splines 48 and 48 are again alined. Uponthe next tappet actuation, the splines 46 abut the splines 48 whereuponthe valve I2 is again opened.

The aforedescribed structure provides a relatively simple and noveltappet construction in which its associated valve is only operated everyother time that the valve tappet is actuated. With this arrangement, itis possible to drive the valve cams at engine speed and have the enginevalves operate onl once every two revolutions of the engine, Also, itmay be desirable in other applications to make the number of ratchetteeth 65 equal to, for example, three or four times the number ofsplines 4% whereby the tap pet must be actuated three or four timesrespectiely for each operation of the valve or other member to bereciprocated. In this way, the tappet can be arranged so that 72operations of the tappet take place for each forward and return movementof the member to be operated,

,where n is any whole number equal to the numher of ratchet teeth 66divided by the number of splines 46. As a further modification, insteadof actuating the tappet member 32 by the rotatable cam member 35, it isalso within the scope of this invention to actuate the tappet member 32by other means-for example, in an engine valve application, by aconventional eccentric driven at engine speed.

While I have described my invention in detail in its present preferredembodiment, it will be obvious to those skilled in the art, afterunderstanding my invention, that various changes and modifications maybe made therein without departing from the spirit or scope thereof. Iaim in the appended claims to coverall such modifloat-ions.

I claim as my invention:

1. Mechanism for operating a first member, said mechanism comprisingsecond and third members, means for extending and retracting said secondmember, said second and third members having means so arranged that inone rotative position of said third member said means abut each other sothat extension and retraction of said second member results in extensionand retraction of said third member for operating said first member, andin another rotative position of said third member said means arearranged to pass each other whereupon extension and retraction of saidsecond member is inoperative to eifect a corresponding operation of saidthird member for operating said first member, and means operative toeffect rotation of said third member upon each extension and retractionof said second member, said last-mentioned means comprising'means forpreventing rotation of said third member except in its retractedposition, an annularmember ax ally movable with and rotatable relativeto said second member and rota-table with and axiall movable relative tosaid third member, anda ratchet wheel, said annular member and ratchetwheel having means including engaging helical splines arranged to effecta predetermined rotation of said third member after each extension andretraction of said second member.

2. Mechanism for extending and retracting a first member; said mechanismcomprising a second member; means for extending and retracting saidsecond member; said members being relatively rotatable so that in onerelative position of said members extension and retraction of saidsecond member is operative to efiect a corresponding movement of saidfirst member and in another relative position of said members extensionand retraction of said second member is inoperative to effect acorresponding movement of said first member; means operative to preventrelative rotation of said members during extension and retraction ofsaid second members and to permit said relative rotation upon completeretraction of said second member; and.

means for relatively rotating said members from one of said relativepositions to the others; said last named means comprising a ratchetmember having helical splines, a spring, a pawl interconcompletion ofsaid retraction said spring efiects relative movement of said membersfrom one of said positions to the other.

FRANK M. KINCAID, JR.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 573,194 Alderson Dec. 15, 1896.959,014 James May 24, 1910 l;185,295 Dresser May 30, 1916 1,347,488Arnold July 27, 1920

